Product Moment Correlation Coefficient (Edexcel A-Level Further Mathematics): Flashcards

How linearly correlated two variables are

$\sum x_i^2 - \frac{(\sum x_i)^2}{n}$

$\sum y_i^2 - \frac{(\sum y_i)^2}{n}$

$\sum x_i y_i - \frac{\sum x_i \sum y_i}{n}$

$r = \frac{S_{xy}}{\sqrt{S_{xx}S_{yy}}}$

Between -1 and 1

Perfect positive linear correlation

Perfect negative linear correlation

No linear correlation between $x$ and $y$

No effect